Question

I am developing an application based on Android 2.1, on one page of my application, there needs an numberpicker. we know that android 2.1 doesn’t contain numberpicker control, so I write one.

I need to show my version of numberpicker on Android 2.1, but the ICS style numberpicker in Android 4.0, to achieve that aim, I used reflection, When in my code, I detected the current Build.VERSION.SDK_INT >= 14, I reflect a numberpicker of the target platform, and add it to current view dynamically.

My question is I can reflect a numberpicker when I run my application on an Android 4.0 platform, but the numberpicker style doesnot appear to be ICS style, Why?

thanks in advance!

Answer 1

If you have the patience you could probably back-port the NumberPicker class. That aside, why use reflection? If you set your target API to 15 this is all you need. In your layout folder declare your alternative number picker. In layout-v11 (NumberPicker is available in API 11 Honeycomb or higher) declare android.widget.NumberPicker. Give each the same ID and in your Activity have something along these lines:

private NumberPicker mNumPicker;
private SomeView mOldNumPicker;

public void onCreate(...) {
    // Use NumberPicker
    if (android.os.Build.VERSION.SDK_INT >= 11) {
        mNumPicker = findViewById(R.id.numpicker);
    } else {
        mOldNumPicker = findViewById(R.id.numpicker);
    }
}

This was you do not need reflection and will not run into any crashes due to accessing non-existent APIs. From here on out you just check if (mNumPicker == null) and if (mOldNumPicker == null) and determine which methods to call based on that. There is also this example of a Number Picker using Buttons and an EditText.